U.S. patent number 6,367,791 [Application Number 09/611,688] was granted by the patent office on 2002-04-09 for substrate mounting system for a three-dimensional modeling machine.
This patent grant is currently assigned to Stratasys, Inc.. Invention is credited to Joseph L. Calderon, Andrew M. Hahn.
United States Patent |
6,367,791 |
Calderon , et al. |
April 9, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Substrate mounting system for a three-dimensional modeling
machine
Abstract
A system for mounting a slab substrate in a three-dimensional
modeling machine includes two parallel rails positioned on opposite
sides of a modeling platform. A blade extends along each rail, each
blade having an inward-facing knife edge. A slab substrate having a
width which approximates the distance between the two rails and
having slits in its sides is loaded in the machine by lining up the
slits, respectively, with each blade and pushing the substrate
towards the rear of the platform as the knife edges cut into the
substrate. Preferably, the platform includes a rear stopper to stop
rearward motion of the substrate. The platform preferably also
includes a retaining means at its front edge that is actuated to
lock the substrate into place on the platform during modeling. The
substrate is removed from the platform by deactuating the retaining
means, if any, grasping the substrate, and sliding the substrate
towards the front of the platform.
Inventors: |
Calderon; Joseph L. (Carlsbad,
CA), Hahn; Andrew M. (Anaheim, CA) |
Assignee: |
Stratasys, Inc. (Eden Prairie,
MN)
|
Family
ID: |
24450030 |
Appl.
No.: |
09/611,688 |
Filed: |
July 7, 2000 |
Current U.S.
Class: |
269/291; 269/900;
29/281.1; 29/281.6 |
Current CPC
Class: |
B29C
64/118 (20170801); B29C 64/106 (20170801); B29C
48/05 (20190201); B29C 64/40 (20170801); Y10T
29/53961 (20150115); Y10S 269/90 (20130101); B29C
48/00 (20190201); Y10T 29/53983 (20150115) |
Current International
Class: |
B29C
67/00 (20060101); B29C 47/00 (20060101); B23Q
003/00 () |
Field of
Search: |
;29/281.1,281.6,283.5
;269/289R,297,299,301,302,303,305,290,291,316,318,231,43,900 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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62-206840 |
|
Sep 1987 |
|
JP |
|
02-015927 |
|
Jan 1990 |
|
JP |
|
Primary Examiner: Hughes; S. Thomas
Assistant Examiner: Compton; Eric
Attorney, Agent or Firm: Kinney & Lange, P.A.
Claims
What is claimed is:
1. An apparatus for removably mounting a slab substrate in a
machine a that builds objects by depositing modeling material onto
the substrate, the apparatus comprising:
a platform for supporting a slab substrate in a defined
configuration, the platform being bound on two opposed sides by a
pair of parallel rails and having an open front end through which a
slab substrate may be slidably loaded onto the platform between the
rails; and
a pair of blades mounted to the rails, each blade having an
inward-facing knife edge protruding past its associated rail so as
to penetrate the sides of a slab substrate being slidably loaded
onto the platform, thereby adhering the substrate to the
platform.
2. The apparatus of claim 1, and further comprising:
a slab substrate having a width which approximates the distance
between the rails and having pre-cut slits in its sides at a height
corresponding to the distance from the platform to the knife edges,
the slits having a depth less than the distance of the protrusion
of the knife edges from the rails.
3. The apparatus of claim 1, and further comprising:
a rear retaining means for confining a slab substrate at a rearward
position of the platform.
4. The apparatus of claim 2, and further comprising:
a front retaining means for confining a slab substrate at a forward
position of the platform.
5. The apparatus of claim 4, and further comprising:
a slab substrate having a width which approximates the distance
between the rails, a length which approximates the distance from
the forward position of the platform to the rearward position
thereof, and having pre-cut slits in its sides at a height
corresponding to the distance from the platform to the knife edges,
the slits having a depth less than the distance of the protrusion
of the knife edges from the rails.
6. An apparatus for removably mounting a slab substrate in a
machine a that builds objects by depositing modeling material onto
the substrate, the apparatus comprising:
a platform for supporting a slab substrate in a defined
configuration, the platform being bound on two opposed sides by a
means for confining and having an open front end through which a
slab substrate may be slidably loaded onto the platform between
said means; and
a pair of blades mounted above the platform on either side thereof,
each blade having an inward-facing knife edge protruding past the
means for confining so as to penetrate the sides of a slab
substrate being slidably loaded onto the platform, thereby adhering
the substrate to the platform.
7. The apparatus of claim 6, and further comprising:
a slab substrate having a width which approximates the distance
between the means for confining and having pre-cut slits in its
sides at a height corresponding to the distance from the platform
to the knife edges.
8. The apparatus of claim 7, wherein the slits have a depth less
than the distance of the protrusion of the knife edges from the
means for confining.
9. The apparatus of claim 6, and further comprising:
a rear retaining means for confining a slab substrate at a rearward
position of the platform.
10. The apparatus of claim 9, and further comprising:
a front retaining means for confining a slab substrate at a forward
position of the platform.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
None.
BACKGROUND OF THE INVENTION
The present invention relates to the fabrication of
three-dimensional objects using additive process modeling
techniques. More particularly, the invention relates to modeling
machines which form three-dimensional objects by depositing
modeling material onto a substrate mounted to a modeling
platform.
Additive process modeling machines make three-dimensional models by
building up a modeling medium, usually in planar layers, based upon
design data provided from a computer aided design (CAD) system. A
mathematical description of a physical part to be created is split
into (usually) planar layers, and those layers are individually
shaped and applied to produce the final part. Three-dimensional
models are used for functions including aesthetic judgments,
proofing the mathematical CAD model, forming hard tooling, studying
interference and space allocation, and testing functionality. The
dominant application of layered manufacturing in recent years has
been for rapid prototyping.
Examples of apparatus and methods for making three-dimensional
models by depositing solidifiable modeling material are described
in Crump U.S. Pat. No. 5,121,329, Batchelder, et al. U.S. Pat. No.
5,303,141, Crump U.S. Pat. No. 5,340,433, Batchelder, et al. U.S.
Pat. No. 5,402,351, Crump et al. U.S. Pat. No. 5,503,785, Abrams et
al. U.S. Pat. No. 5,587,913, Danforth, et al. U.S. Pat. No.
5,738,817, Batchelder, et al. U.S. Pat. No. 5,764,521 and Comb et
al. U.S. Pat. No. 5,939,008, all of which are assigned to
Stratasys, Inc., the assignee of the present invention. An
extrusion head extrudes solidifiable modeling material in a fluent
strand (also termed a "bead" or "road") from a nozzle onto a base.
The base comprises a modeling substrate which is removably affixed
to a modeling platform. The extruded material is deposited
layer-by-layer in areas defined from the CAD model, as the
extrusion head and the base are moved relative to each other by
mechanical means in three dimensions. The finished model is removed
from the substrate. A solidifiable material which adheres to the
previous layer with an adequate bond upon solidification is used as
the modeling material. Thermoplastic materials have been found
particularly suitable for these deposition modeling techniques.
Other additive process manufacturing techniques include depositing
UV curable polymers as in Masters U.S. Pat. No. 5,134,569; jetting
of droplets of material as in Helinski U.S. Pat. No. 5,136,515;
extruding a seable plastic in vertical strips as in Valaaara U.S.
Pat. No. 4,749,347; laser welding deposition as in Pratt U.S. Pat.
No. 5,038,014; stacking and adhering planar elements as in DiMatteo
U.S. Pat. No. 3,932,923; and applying shaped layers of paper as in
Hull U.S. Pat. No. 5,192,559.
In additive process three-dimensional modeling machines utilizing
manufacturing techniques such as those described above, the model
is built up on a base comprising a substrate mounted on a modeling
platform. The material being deposited must adhere to the substrate
to form a foundation layer over which the remaining layers of the
object are deposited. The substrate stabilizes the model as it is
built up, and facilitates removal of the model from the modeling
machine when the model is complete.
It is preferred that parts deposited on the modeling substrate be
strongly adhered thereto to overcome two effects. First, strains
generated within the extruded material tend to warp the deposited
structures unless the structures are supported in their correct
orientation. The substrate is important in serving to avoid
localized shrinkage in the foundation layer. Second, in some
deposition processes, there are forces such as pull from an
extrusion nozzle and centripetal acceleration on parts that are not
stationary, that tend to distort the deposited structures. A
delamination of the foundation layer from the substrate during the
building of the object could result in a total failure in forming
the object. Further, since the removable substrate becomes a
defining surface for the object being built, it must be held in a
well-defined configuration. Typically, the substrate is held in a
configuration approximating a plane.
The Crump '329 and '433 patents disclose a foam plastic material
for use as a modeling substrate. A blue polystyrene material
manufactured by Dow-Corning Corp. under that name and having a
compression strength of 30 psi is identified as particulary
suitable coarse, porous structure. The Crump '329 and '433 patents
also disclose modeling on a wire mesh sandpaper substrate, and on a
water soluble wax. The Batchelder et al. '521 patent discloses a
sheet of magnetic material for use as a modeling substrate, wherein
the modeling platform includes a magnet for attracting the sheet,
while the Comb '008 patent discloses a flexible sheet substrate
held down by vacuum forces.
In rapid prototyping systems sold in the past by Stratasys, Inc., a
preferred substrate material has been a polymer foam. A foam slab
substrate has proven particularly suitable for supporting models
made by extrusion-based deposition modeling techniques. The
porosity and compressibility of foam allows foundation layers of
modeling material to be buried into the foam, which increases
stability of the model as is it built up. The foam substrate is
mounted onto a tray outside of the modeling machine. Up to eight
spears are inserted through side walls of the tray and pressed into
the foam to engage the foam from all sides. The tray is then placed
on the modeling platform within the modeling machine, and locked
into place. After the object is formed, the tray is removed from
the modeling machine and the foam is broken away from the
object.
While foam substrates have found substantial use, mounting the foam
into a modeling machine with spears requires the user to spend time
that could be better spent modeling. Additionally, the spears can
be lost when not in use. Further, the foam materials used in the
prior art produce dust when broken away from the object. The
presence of dust creates a risk that the dust may contaminate
bearings and bushings in the modeling machine.
SUMMARY OF THE INVENTION
The present invention is an apparatus and method for mounting a
substrate to the modeling platform of a machine that builds up
three-dimensional objects of predetermined design depositing
solidifiable material on the substrate. The substrate mounting
system of the present invention includes two parallel rails
positioned on opposite sides of a modeling platform. A blade
extends along each rail, each blade having an inward-facing knife
edge. A slab substrate having a width which approximates the
distance between the two rails and having slits in its sides is
loaded in the machine by lining up the slits with each knife edge
and pushing the slab towards the rear of the platform as the knife
edges penetrate the slab. Preferably, the platform includes a rear
stopper to stop rearward motion of the substrate. The platform
preferably also includes a retainer or retainers at its front edge
that lift up to lock the substrate into place on the platform
during modeling. The substrate is removed from the platform by
releasing the front edge retainers, if any, grasping the substrate,
and sliding the substrate towards the front of the platform.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic of a representative generic extrusion-based,
layered deposition modeling system.
FIG. 2 is a perspective view of the preferred embodiment of the
invention, before a substrate is mounted on the modeling
platform.
FIG. 3 is a perspective view of the preferred embodiment of the
invention, after a substrate is mounted on the modeling
platform.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a generic representation of a extrusion-based layered
modeling system 106, of a type known in the art, in which the
present invention may be used. A computer aided design (CAD)
program resident in a processor 108 generates a file describing the
geometry of a part 109 to be created. A slicing program (shown as
resident in processor 108 but which may alternatively be resident
in a separate processor) algorithmically subdivides the file into
volume elements 110 corresponding to shapes that can be extruded
from a nozzle. Additional volume elements 112 are added as
necessary to provide mechanical support to a part during its
construction. The volume elements are sequentially ordered so that
deposited material is supported appropriately.
An electronic controller 116, in response to receiving
three-dimensional shape data from processor 108 over line 114,
controls the extrusion of modeling material in an xyz-coordinate
reference frame so that beads of modeling material are extruded
layer-by-layer in a pattern defined by the volume elements 110 and
112. Controller 116 sends control signals to an x-y axis translator
118, a z-axis translator 120 and an extrusion pump 122, over output
signal lines 117a, 117b and 117c, respectively. X-y axis translator
118 is an electromechanical device that moves a robotic arm 124, so
as to sequentially position an extrusion head 126 carried by the
arm 124 within an x-y plane with respect to a modeling substrate
128. Extrusion pump 122 synchronously provides modeling material
from a material supply 130 to extrusion head 126. The extrusion
head 126 terminates in a nozzle 132 through which the modeling
material is extruded.
The modeling material is extruded from nozzle 132 onto the
substrate 128, which is removably mounted onto a modeling platform
134. Modeling platform 134 moves in a z-direction under the control
of z-axis translator 120. Z-axis translator 120 incrementally
lowers modeling platform 134 following deposition of a layer of
modeling material, to build up a model 136 on the substrate 128.
After the model 136 is created, the model 136 is removed from the
modeling system 106 and from the substrate 128.
In the generic representation shown, the extrusion head 126 is
movable in a horizontal plane in x and y directions, while the
modeling platform 134 is movable in a vertical z-direction. It is
recognized in the art, however, that any three-dimensional relative
movement of the extrusion head 126 and the modeling platform 134
may be implemented to create a three-dimensional object by
extrusion-based manufacturing.
A substrate mounting system is now described which has application
for mounting a slab substrate in an additive process
three-dimensional modeling system, such as the type described above
and shown in FIG. 1. It should be understood, however, that the
teaching of this invention is not limited for use only with an
extrusion-based layered manufacturing apparatus of the type shown.
That is, the invention can be used to advantage in other types of
additive process three-dimensional modeling machines, such as those
identified in the background section herein.
A preferred embodiment of the substrate mounting system of the
present invention is shown in FIG. 2. A z-axis stage 140 includes a
horizontal modeling platform 142 for supporting a slab substrate
144. As shown, the z-axis stage 140 is made of cast metal and the
platform 142 has open spaces, which reduce the materials cost and
the weight of the platform. Those skilled in the art will recognize
the platform 142 may alternatively be solid and that numerous other
variations in the configuration of platform 142 are possible, so
long as the platform will support a slab substrate 144 in a defined
configuration on which to build a model.
A rear stopper 146 extends upward from the rear of modeling
platform 142. The rear stopper 146 is formed of two rigid
projections in the embodiment shown, but alternative configurations
will be recognized by those skilled in the art, such as a solid
wall, a gate or a rotating retainer. Two parallel rails 148 are
mounted on opposed sides of the platform 142, and define a
substrate mounting area extending generally from a front end of the
platform to the rear thereof. A pair of blades 150 extend along
each rail 148, and are mounted to the top of each rail 148 by
fasteners 152. Each blade 150 has two knife edges 154, at either
end of the blade, which extend horizontally from the blade 150 and
face each other. Desirably, the knife edges 154 have a thickness
that is greater than the thickness of the blade 150 in between the
knife edges 154, to lessen the force required in mounting and
removing the substrate 144 as described below.
A slab substrate 144 for use in the present invention (as shown in
FIG. 1) has a width w that approximates the distance between the
two rails 148, and a length l that approximates the length of the
rails 148. Substrate 144 further has a slit 156 pre-cut into each
of two opposite sides thereof, at a height h. Height h corresponds
to the vertical distance from the platform 142 to the blades 150.
Each slit 156 extends the length l of the substrate 144, from a
leading edge 157 to a trailing edge 159. Each slit 156 is
preferably slightly less deep than the distance of the protrusion
of knife edges 154 from the rails 148. The upper and lower surfaces
of substrate 144 approximates a plane.
A user loads substrate 144 onto platform 142 by aligning the
leading edge 157 of the substrate 144 with the blades 150 so that
the blades 150 mate with the slits 156. The user pushes the
substrate 144 towards the rear of the platform 142 as the knife
edges 154 of blades 150 penetrate the substrate 144 at the position
of the slits 156. The user continues to push until a hard stop is
reached, by the action of the substrate 144 pushing against rear
stopper 146. The substrate 144 is then bound on its sides by the
rails 148, bound at its leading edge 157 by rear stopper 146, and
adhered to the platform 142 by blades 150. Friction prevents the
foam from moving in the x-y plane. For added assurance that the
substrate 144 will not slide forward during modeling, the substrate
is bounded on its trailing edge 159 by a pair of retainers 158.
Each retainer 158 is rotatably mounted to the front of platform 142
by a fastener 160, and includes a grip 162. After the substrate 144
is mounted on the platform 142, the user grasps the grips 162 to
rotate retainers 158 into an upward position. FIG. 3 shows the
substrate 144 mounted on the modeling platform 142.
A low-dusting polymer foam having good compression strength is a
preferred material to be utilized as the slab substrate 144. The
low-dusting characteristic is desirable so as to reduce user clean
up time and reduce risk of machine contamination. Those skilled in
the art will recognize that other materials which share similar
characteristics as a polymer foam could be used as well.
The slits 156 reduce the force required by the user to install the
substrate 144, help to guide the substrate 144 onto the platform
142, and also reduce the amount of dusting created by knife edges
154 cutting into the substrate 144. The substrate loading apparatus
of present invention may, however, be practiced to some advantage
using a substrate 144 that does not have pre-cut slits. Conversely,
a slit 156 can be cut into all four sides of the substrate 144 if
desired, to provide flexibility in the orientation of the substrate
144 on the platform 142.
The design of blades 150 wherein the blades 150 are thin in between
the knife edges 154 similarly reduces the force required by the
user to install the substrate 144, by reducing frictional forces
against the substrate. Alternatively, knife edges 154 could extend
the entire length of blades 150.
Although the present invention has been described with reference to
preferred embodiments, workers skilled in the art will recognize
that changes may be made in form and detail without departing from
the spirit and scope of the invention.
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